Telephone-transmitter.



Patented Apr. 2, 1912.

COLUMBIA PLANOORAPH C0 WASHINGTON, D. C.

MATTHEW MOLONEY, OF CHRISTCHURCH, NEW ZEALAND.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented Apr. 2, 1912.

Application filed. October 25, 1909. Serial No. 524,478.

To all whom it may concern:

Be it known that I, MATTHEW MOLONEY, a subject of His Majesty the King of Great Britain and Ireland, and residing at Ferry Road, Christchurch, in the Provincial District of Canterbury, in the Dominion of New Zealand, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a specification.

The invention relates to telephone transmitters, and the object is to enable persons to speak over longer distances with an increased volume of sound than hitherto.

-According hereto the casing of the transmitter contains a metal cylinder insulated from the casing and having within it a similarly shaped carbon cup carrying a plurality of radially arranged carbon pencils with pointed ends fitting in a groove in a carbon center stud. The stud has a point which passes through the center of two carbon washers having between them a number of small shot or pellets. The washers are kept in position by a carbon recessed ring within which and against the face of the usual metal transmitting diaphragm are located a number of pellets or grains of carbon arranged around the point of the carbon stud which just clears said diaphragm. A transmission screw insulated from the casing is connected to the cup.

My invention is illustrated in the accompanying drawing wherein Figure 1, is a vertical central sectional elevation, Fig. 2, an end sectional elevation on A-A, Fig. 1, and Figs. 3 and l similar sectional views on the lines CC and B-B respectively of Fig. 1, Fig. 5, is a vertical central sectional elevation of anotherform of telephone transmitter fitted with my invention. Fig. 6, a front elevation with the front of the casing removed, and Fig. 7, a corresponding view with front of the easing diaphragm and other parts removed.

Referring first to Figs. 1 to .4, the outer casing 1 of the transmitter instrument has within it the metal cylinder 2 within which is the carbon cup 3 having the carbon pencils 4L projecting radially inward from a ring of holes in said cup. The points of these pencils rest loosely in a circumferential groove '5 formed in a collar 6 upon a carbon center stud 7. The metal transmission rod 8 is secured by solder or otherwise to the cylinder 2 and passes through an insulating sleeve 9 designed to insulate it from the casing, and screws at its end into a nut cap 10, fitting an insulating washer 11 in the casing tube 12. The connector sleeve 13 fits around rod 8 and has connected to it the transmission wire 14 which is one of the wires in the usual electrical circuit. The stud 7 has a conical point 15 upon which is placed a carbon washer 16 fitting the cup 3, and resting lightly against the collar 6. A second carbon washer 17 fits upon the point 15, and rests against the face of the cup 3. The portion of said washer bearing against the cup is suitably insulated from the cup. A layer of small shot 18 or grains of carbon is placed between the washers l6 and 17. A recess ring 19 of carbon keeps the washers 16 and 17 in position, and is retained by a cap 20 of insulating material which screws upon the cylinder 2. The point 15 is arranged just to clear the diaphragm 21 (which is common to transmitting instruments) and a layer 22 of carbon grains is placed within said ring around the point 15 resting against the said diaphragm. The diaphragm is in electrical connection through the casing 1 of the instrument with the electrical circuit wire 23 known as body wire) and completing the circuit with the wire connected to sleeve 13. Electric impulses flow through the instrument over the following circuit: from the wire 23 through the casing to the diaphragm 21 and carbon grains 22 to the point 15 of the stud and then directly through the stud to the wire 14, a portion of the current passing also through the collar (5 and pencils 4: to the cup 3 and cylinder 2 on the stud. The employment of the carbon pencils and the parts arranged in the manner described provides a very sensitive instrument giving very strong electrical impulses when the diaphragm is vibrated. It has been found that carbon in pencil form is particularly useful in such instruments, and by providing a se ries of these pencils, as hereinbetore described, the volume of sound obtainable from a transmitter is greater than when the carbon employed is in other forms. The pencils being of carbon and there being a relatively large number thereof a much greater working capacity is obtained than if a single carbon center stud is used. As soon as current flows through the instrument vibration is set up and the pencil being loose insures good clean contact. Should a section of the transmitter by any chance get out there is always a certainty of contact being obtained by the remaining parts.

A similar arrangement of the cylinder, cup, pencils, center stud, carbon washers and other parts described can be employed in other types of transmitters such for instance as those known as American solid backs.

To show how the invention can be adapted to suit Various transmitter casings, I illustrate in Figs. 5, 6, and 7, to which I will now refer my invention as applied to a transmitter known to experts as the solid back which is hereby converted into a loose back transmitter. The casing 24'has the removable front 25 to which is connected the metal bridge 26 in the usual way. The metal cylinder 27 closed at one end has a projection 28 which fits a hole in the bridge and has within it the carbon cup 29 provided with a number of radially arranged carbon pencils 30 projecting radially inward from a ring of holes in the cup and having points 31 fitting loosely into a groove 32 formed in the carbon center stud 33, which has a stem 34 fitting a hole in the cup 29. A carbon washer 35 fits upon said center stud and rests lightly against the face of the end of the cup 29. A recessed carbon ring 36 fits within the cylinder 27 and upon the center stud, and has within it a cylinder 37 of paper or other insulating material. Between washer 35 and ring 36 is a layer 38 of small. shot or pellets.

The recess of ring 36 contains carbon grains 39 kept therein by a disk 40 of carbon s cured to a screw pin 41 which passes through the transmitting diaphragm 42 and has the nut 43 upon its end. An insulating washer 44 of mica upon the back of disk 40 fits upon a screw threaded shoulder 45 of pin 41 and is clamped thereon by nut 46 to which is connected the transmitter wire 47 leading to a coupler 48 upon the insulating block 49 attached to the bridge, where it is connected to the wire 50 of the usual telephone circuit which passes through the casing. The insulating washer 44 is clamped against the face of carbon ring 36 by a screw cap 51, screwing upon the end of cylinder 27. The opposite wire of the circuit is in electrical connection with the easing of the transmitter in the ordinary way and the bridge 26 is in electrical connection with the casing.

To secure the best efiect the carbon center stud, washers and carbon pencils must be all highly polished.

What 1 do claim and desire to secure by Letters Patent of United States is 1. In a telephone transmitter, the combi-- nation of a metal cylinder, a carbon cup therein, carbon pencils projecting radially inward from holes in said cup, a carbon center stud, having a groove therein receiving the points of said pencils, carbon washers on the point of said center stud, pellets between said washers, granulated carbon around the point of said stud, means for retaining said granulated carbon in place, a screw pin connected to the transmitting diaphragm, a carbon disk secured to said screw pin, and a transmission screw with which one of the circuit wires is in electrical connection, substantially as specilied.

2. In a telephone transmitter, the combination of a metal cylinder, a carbon cut therein, carbon pencils projecting radially inward from holes in said cup, a carbon center stud, having a groove therein receiving the points of said pencils, carbon washers on the point of said center stud, pellets between said washers, granulated carbon around the point 01": said stud, means for retaining said granulated carbon in place, a screw pin connected to the transmitting diaphragm, and a carbon disk secured to said screw pin.

3. In a telephone transmitter, the combi. nation of a metal cylinder, a carbon cup therein, carbon pencils projecting radially into said cup, a carbon center stud, having a groove therein receiving the points of said pencils, carbon washers on the point of said center stud, pellets between said washers, granulated carbon around the point of said stud, and means for retaining said granulated carbon in place, substantially as specified.

4. In transmitting apparatus of telephones, the combination of a carbon cup, carbon pencils projecting radially into said cup, and a center stud having a groove receiving the points of said pencils, substantially as set forth herein and illustrated.

5. In transmitting apparatus of telephones, in combination a pointed center name to this specification in the presence of stud, carbon Washers upon the point of said two Witnesses.

stud, and a layer of pellets between said MATTHEW MOLONEY. Washers substantially as set forth herein Witnesses: and illustrated. GEORGE ALFRED JAMES HART,

In testimony whereof I have signed my JOHN HAZLITT UPI-IAM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

